A battery (any 12volt battery, including leisure) is considered fully charged at 12.6 volts at rest. At a temperature of between 5 to 20c. Any lower and it is in a ‘discharge’ state.
No vehicle, or for that matter any charger, can recharge to more than 90 to 95% charge outside of lab conditions.
Check your battery after charging and it will show anything from 12.6 to 14 volts. However within a short time, about 15 mins usually does it, it will settle to its natural state. This state will vary dependent on age, temperature, physical condition.
Then you will have an accurate reading. 12.6 is perfect, 12.2 is acceptable.
In the systems describe above the vehicle system will recharge or ‘top up’ the battery to it’s natural state.
Any vehicle battery should be charged at 10% of it’s ampere hour rating, NOT it’s CCA rating which is different.
And if cold weather use is a concern you should fit a larger CCA rated battery than standard to allow for amperage drop in sub zero temperatures.
e.g your vehicle may have a 300CCA battery. Which means it will provide 300 amps for 30 secs at 0.c But in sub zero temperatures this can drop to as little as 200 amps for the same 30 secs.
For sub zero use we always recommended going up by 50% when replacing the battery. 300 to 450, 500 to 750 etc. This will provide the required power when you need it most without putting undue strain on the vehicle system.
And carry jump leads!
KISS will get you out of trouble… can be fixed with chewing gum and knicker elastic.. and is cheaper!